Method and compositions for treatment of parkinsonism syndrome in mammals

ABSTRACT

This invention provides a method for treating the symptoms of parkinsonism which comprises administering to a human or other mammal suffering from the symptoms of parkinsonism an effective amount of a compound selected from the group consisting of optically-active or racemic compounds represented by the general formula: ##STR1## wherein R 1  is selected from the group consisting of organic radicals methyl, substituted or unsubstituted phenyls, pyridyl, hydroxyphenyl, ##STR2## X is oxygen or sulfur, Y is selected from the group consisting of hydroxy, nitro, cyano, azido, amino, acylamino, carboxyamido, trifluoromethyl, sulfate, sulfonamido, halogen, hydrocarbyl and hetero atom-substituted hydrocarbyl radicals, wherein said heteroatoms are selected from the group consisting of halogen, nitrogen, oxygen, sulfur and phosphorus and said hydrocarbyl radicals comprise from 1 to 12 carbon atoms. and a is an integer of from zero to 3, 
     R 2 , R 3  and R 4  are each selected from the group consisting of H and OA, A is H or is selected from the group consisting of hydrocarbyl radicals, ##STR3## R 5  is selected from the group consisting of hydrocarbyl radicals; n is an integer between 1 and 3; and R 6  is an alkyl chain having between 1 and 3 carbon atoms with the provision that at least one of R 2 , R 3  and R 4  is H, that at least one of R 2 , R 3  and R 4  is not H, and that R 2  and R 4  are not both OA, and pharmaceutically acceptable salts thereof. Preferably, R 2  is oxygen. 
     Preferably, R 2  is OA and A is H, and the compound is the (-) isomer.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation in part of U.S. patentapplication Ser. No. 640,685, filed on Aug. 13, 1984, and U.S. patentapplication Ser. No. 811,768, filed on Dec. 20, 1985, in the name ofAlan S. Horn.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods of treating mammals to alleviate thesymptoms of parkinsonism. This invention also provides compositionsuseful in such method.

2. Background of the Art

Parkinson's disease is a prevalent, serious neurological disease thatafflicts approximately one-half million persons in the United Statesalone and more than 90 percent of the time the disease becomes manifestafter the age of 55. There is no clear evidence that Parkinson's diseaseis determined by genetic factors and research is underway to discoverpossible environmental causes, such as infections or toxins.

Administration of one toxin, MPTP(N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), causes a syndrome thatresembles Parkinson's disease when administered to primates. TheMPTP-induced parkinsonism syndrome is similar to the idiopathic disease,both pathologically and biochemically, and it responds favorably to theadministration of levo-dopa.

Toxic substances like MPTP may be widespread in the environment andthere is concern that the accumulated effect of such toxins togetherwith the effects of aging will contribute to development ofparkinsonism. (Blume, E., "Street Drugs Yield Parkinson's model, JAMA,1983, 250, 1314.)

Certain drugs which present the action of dopamine in the basal gangliaof the brain produce a parkinsonism-like syndrome as a side effect. Forexample, antipsychotic drugs such as the phenothiazines andbutyrophenones block postsynaptic receptors for dopamine and causesymptoms that resemble parkinsonism. On the other hand, reserpineproduces a parkinsonism-like condition by depleting dopamine availablefor release by the presynaptic neuron. Certain rare disorders, such ascarbon monoxide or manganese poisoning, Wilson's disease and Shy-Dragersyndrome, exhibit a parkinsonism-like syndrome as one aspect of a morewidespread cerebral disorder.

Whatever its etiology, Parkinson's disease appears late in life and ischaracterized by loss of smooth control of voluntary muscles. Smoothcontrol of voluntary movements is usually attributed to a balance of twoneurotransmitters in the striatal tracts of the basalganglia--dopaminergic components for inhibitory function, andcholinergic components for excitatory function. Imbalance in theseindividual systems produces disorders of movement and the disabilitiesof movement in parkinsonism are attributed to a deficiency in thedopaminergic component caused by the loss of neurons in the basalganglia. By contrast the hyperkinesis characteristic of Huntington'schorea is thought to result from excessive dopaminergic activity in thebasal ganglia. (Calne, D. B. "Parkinsonism, Clinical andNeuropharmacologic Aspects," Postgrad. Med., 1978, 64, 82-88.)

Consequently, the goal of treatment fo parkinsonism is to balancestriatal activity by reducing cholinergic activity or to augmentdopaminergic function with centrally-active drugs levodopa orL-3,4-dihydroxyphenylalanine.

At present, for example, the most effective treatment of parkinsonism isachieved by levodopa, however many patients experience undesirable sideeffects such as nausea, vomiting, cardiac arrhythmias, abnormalinvoluntary movements and psychiatric disturbances. Therefore, there isa continuing search to find useful analogs of dopamine for the treatmentof Parkinson's disease or the syndrome known as parkinsonism. Two knownclasses of dopamine analogs are the aporphines and the ergolines, andthe need exists for novel and improved dopaminergic analogues capable ofuse in treating the symptoms of parkinsonism.

SUMMARY OF THE INVENTION

This invention provides a method for treating the symptoms ofparkinsonism in mammals, e.g., humans, to reduce or reverse the symptomsof parkinsonism, which comprises administering to a mammal sufferingfrom parkinsonism an effective amount of a compound selected from thegroup of racemic or optically active compounds represented by thegeneral formula: ##STR4## wherein R₁ is selected from the groupconsisting of organic radicals methyl, substituted or unsubstitutedphenyls, pyridyl, hydroxyphenyl, ##STR5## X is oxygen or sulfur, Y isselected from the group consisting of hydroxy, nitro, cyano, azido,amino, acylamino, carboxyamido, trifluoromethyl, sulfate, sulfonamido,halogen, hydrocarbyl and hetero atom-substituted hydrocarbyl radicals,wherein said heteroatoms are selected from the group consisting ofhalogen, nitrogen, oxygen, sulfur and phosphorus and said hydrocarbylradicals comprise from 1 to 12 carbon atoms, and a is an integer of fromzero to 3,

R₂, R₃ and R₄ are each selected from the group consisting of H and OA, Ais H or is selected from the group consisting of hydrocarbyl radicals,##STR6##

R₅ is selected from the group consisting of hydrocarbyl radicals; n isan integer between 1 and 3; and R₆ is an alkyl chain having between 1and 3 carbon atoms with the provision that at least one of R₂, R₃ and R₄is H, that at least one of R₂, R₃ and R₄ is not H, and that R₂ and R₄are not both OA, and pharmaceutically acceptable salts thereof.Preferably, R₂ is oxygen.

It is essential that the compound selected for use in the method of thepresent invention be an optically active compound or racemic mixturethereof capable of selectively activating the postsynaptic D₂ dopaminereceptor, e.g., in a human. In particular, it is found that the (-)enantiomer of 5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino)tetralinis especially preferred for use in the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The compounds used in the present invention are selected from the groupof steroisomers or mixtures thereof of compounds represented by thegeneral formula: ##STR7## wherein R₁ is selected from the groupconsisting of organic radicals methyl, substituted or unsubstitutedphenyls, pyridyl, hydroxyphenyl, ##STR8## X is oxygen or sulfur, Y isselected from the group consisting of hydroxy, nitro, cyano, azido,amino, acylamino, carboxyamido, trifluoromethyl, sulfate, sulfonamido,halogen, hydrocarbyl and hetero atom-substituted hydrocarbyl radicals,wherein said heteroatoms are selected from the group consisting ofhalogen, nitrogen, oxygen, sulfur and phosphorus and said hydrocarbylradicals comprise from 1 to 12 carbon atoms, and a is an integer of from0 to 3,

R₂, R₃ and R₄ are each selected from the group consisting of H and OA, Ais H or is selected from the group consisting of hydrocarbyl radicals,##STR9##

R₅ is selected from the group consisting of hydrocarbyl radicals; n isan integer between 1 and 3; and R₆ is an alkyl chain having between 1and 3 carbon atoms with the provision that at least one of R₂, R₃ and R₄is H, that at least one of R₂, R₃ and R₄ is not H, and that R₂ and R₄are not both OA, and pharmaceutically acceptable salts thereof.Preferably, R₂ is oxygen.

A is preferably H or is selected from the group consisting of phenyl andalkyl radicals having from 1 to 12 carbon atoms, and more preferably R⁵is an alkyl or aryl radical that would serve to extend the activity ofthe compound in the body, for example phenyl, methyl t-butyl,d-methylphenyl, o-, m- or p-methoxyphenyl, or nonyl.

The more preferred groups represented by R₁ are thienyl, phenyl,hydroxyphenyl, furanyl and naphthalenyl, e.g., 2-thienyl, 3-thienyl,3-hydroxyphenyl, 4-hydroxyphenyl, etc.

In the more preferred compounds for use in the present invention n is 2and R₂ is OA; and most preferably A is H and R₆ is propyl.

It is essential that the compound selected for use in the method of thepresent invention be an optically active or racemic compound capable ofselectively activating the postsynaptic dopamine D₂ receptor, e.g., in ahuman. In particular, it is found that the (-) isomer of5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino) tetralin isespecially preferred for use in the method of the present invention.

The above compounds may be made by any of the methods disclosed in U.S.Pat. No. 4,564,628 entitled "Substituted 2-Aminotetralins," which ishereby incorporated by reference. A method for resolving the compoundsinto (+) and (-) isomers is disclosed in Example 1 hereinafter.

For purposes of this invention, designation of the (-) isomer shall meanthat the (-) isomer is present in excess of the (+) isomer. Preferably,the mixture is greater than 90 mole percent of the (-) isomer. Mostpreferably, the (-) isomer is substantially pure, i.e., greater than 99mole percent.

Particularly preferred compounds are as follows:

Compounds wherein R₁ is selected from the group consisting of radicalsrepresented by the general formula: ##STR10## wherein X is oxygen orsulfur. Specific preferred compounds of this group include:

2-(N-n-propyl-N-2-[2-thienyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[3-thienyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-furanyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[3-furanyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-thienyl-4-methyl]ethylamino-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-thienyl-3,4,5-trimethyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-thienyl-5-chloro]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-(4-bromo-5-methyl)thienyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-(4-methyl-5-ethyl)thienyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-benzothienyl]ethylamino)-5-hydroxytetralin and

2-(N-n-propyl-N-2-[3-benzothienyl]ethylamino)-5-hydroxytetralin.

Compounds wherein R₁ is selected from the group of radicals representedby the general formulae: ##STR11## wherein Y and a are as defined above.More preferably, Y comprises no more than 5 carbon atoms and a is 0or 1. Specific preferred compounds of this group include:

2-(N-n-propyl-N-2-[2-naphthalenyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[4-indolyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[2-benzothienyl]ethylamino)-5-hydroxytetralin,

and

2-(N-n-propyl-N-2-[3-benzothienyl]ethylamino)-5-hydroxytetralin;

Compounds wherein R¹ is phenyl and/or substituted phenyl and is selectedfrom the group of radicals represented by the general formula: ##STR12##wherein Y and a are as defined above. Specific preferred compounds ofthis group include:

2-(N-n-propyl-N-2-[phenyl]ethylamino)-5-hydroxytetralin,

2-(N-n-propyl-N-2-[4-hydroxyphenyl]ethylamino)-5-hydroxytetralin,

and

2-(N-n-propyl-N-2-[3-hydroxyphenyl]ethylamino)-5-hydroxytetralin;

This invention provides a method of treatment of the symptoms ofparkinsonism which comprises administering a therapeutically effectiveamount of one of the foregoing compounds to a patient suffering suchsymptoms. Even more preferably, the method of the present inventioncomprises administering the (-) isomer of5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino)tetralin to a human orother mammal to reduce the symptoms of parkinsonism.

Parkinsonism, as used herein, signifies a condition characterized by thesymptoms to which the term Parkinson's disease refers--tremor,bradykinesia, rigidity, and a disturbance of posture. As used herein,"tremor" refers to the rhythmically alternating contractions (usuallythree to five per second) of a muscle group and its antagonist. Tremoroften disappears on purposeful movement and usually increases remarkablywith anxiety or stress. "Bradykinesia," as used herein, is characterizedby decreased control in spontaneous movement, loss of normal associatedmovements, and slow initiation of all voluntary movements. "Rigidity" asused herein, is an intermittent resistance to passive movement ofextremities that is often characterized as a "cogwheel" or "ratchet"resistance. In general, a pharmacologically-effective daily dose can befrom 0.01 mg./kg. to 100 mg./kg. per day, bearing in mind, of course,that in selecting the appropriate dosage, in any specific case,consideration must be given to the patient's weight, general health,metabolism, age and other factors which influence response to the drug.A particularly preferred dose is 1.0 mg./kg. per day.

Another embodiment of this invention is the provision of pharmaceuticalcompositions in dosage unit form which comprise from about 2 mg. to 500mg. of a compound of the above formula.

The pharmaceutical composition may be in a form suitable for oral use,for example, as tablets, aqueous or oily suspensions, dispersiblepowders or granules, emulsions, hard or soft capsules, or syrups orelixirs. Compositions intended for oral use may be prepared according toany method known to the art for the manufacture of pharmaceuticalcompositions and such compositions may contain one or more agentsselected from the group consisting of sweetening agents, flavoringagents, coloring agents, and preserving agents in order to provide apharmaceutically elegant and palatable preparation. Tablets contain theactive ingredient in admixture with non-toxic pharmaceuticallyacceptable excipients which are suitable for manufacture of tablets.These excipients can be, for example, inert diluents, for examplecalcium carbonate, sodium carbonate, lactose, calcium phosphate, orsodium phosphate; granulating and disintegrating agents, for examplemaize starch, or alginic acid; binding agents, for example starch,gelatine, or acacia; and lubricating agents, for example magnesiumstearate, stearic acids, or talc. The tablets can be uncoated or theycan be coated by known techniques to delay disintegration and adsorptionin the gastrointestinal tract and thereby provide a sustained actionover a longer period.

Formulations for oral use may also be presented as hard gelatinecapsules wherein the active ingredient is mixed with an inert soliddiluent, for example calcium carbonate, calcium phosphate, or kaolin, oras soft gelatin capsules wherein the active ingredient is mixed with anoil medium, for example archis oil, liquid paraffin, or olive oil.

Aqueous suspensions contain the active compound in admixture withexcipients suitable for the manufacture of aqueous suspensions. Suchexcipients are suspending agents, for example sodiumcarboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose,sodium alginate, polyvinylpyrrolidone, gum tragacanth, and gum acacia;dispersing or wetting agents may be naturally-occurring phosphatides,for example lecithin, or condensation products of an alkylene oxide withfatty acids, for example polyoxethylene stearate, or condensationproducts of ethylene oxide with long chain aliphatic alcohols, forexample heptadecethyleneoxy-cetanol, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol, for example, polyoxyethylene sorbitol monooleate, orcondensation products of ethylene oxide with partial esters derived fromfatty acids and hexitol anhydrides, for example polyoxyethylene sorbitanmonooleate. The aqueous suspensions may also contain one or morepreservatives, for example ethyl, n-propyl, or p-hydroxy benzoate, oneor more coloring agents, one or more flavoring agents and one or moresweetening agents, such as sucrose, saccharin, or sodium or calciumcyclamate.

Dispersible powders and granules suitable for preparation of an aqueoussuspension by the addition of water provide the active ingredient inadmixture with a dispersing or wetting agent, suspending agent and oneor more preservatives. Suitable dispersing or wetting agents andsuspending agents are exemplified by those already mentioned above.Additional excipients, for example, sweetening, flavoring and coloringagents may also be present.

Syrups and elixirs may be formulated with sweetening agents, for exampleglycerol, sorbitol or sucrose. Such formulations may also contain ademulcent, preservative, flavoring and coloring agents. Thepharmaceutical compositions may be in the form of a sterile injectablepreparation, for example as serile injectable aqueous suspension. Thissuspension may be formulated according to the known art using thosesuitable dispersing or wetting agents and suspending agents which havebeen mentioned above. The sterile injectable preparation may also be asterile injectable solution or suspension in a non-toxicparenterally-acceptable diluent or solvent, for example, as a solutionin 1,3-butane diol.

The pharmaceutical compositions may be tableted or otherwise formulatedso that for every 100 parts by weight of the composition there arepresent between 5 and 95 parts by weight of the active ingredient. Thedosage unit form will generally contain between about 1 mg. and about100 mg. of the active ingredient of the formula stated above.

From the foregoing discussion of formulations it is apparent that thecompositions of this invention can be administered orally orparenterally. The term parenteral as used herein includes subcutaneousinjection, intravenous, intramuscular, or intrasternal injection orinfusion techniques. The compositions can also be administeredtransdermally by topical administration to skin and mucosal membranes.

To illustrate the manner in which the invention may be carried out, thefollowing examples are given. It is understood, however, that theexamples are for the purpose of illustration and the invention is not tobe regarded as limited to any of the specific materials or conditionstherein.

Animal test models for evaluating postsynaptic dopaminergic receptorfunction in the central nervous system were used to compare the effectsof the (+) and (-) stereoisomers of5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino)tetralin (N-0437). Itis believed that it is desirable for the treatment of parkinsonism thatthe dopaminergic agent selectively activate the postsynaptic receptor.

EXAMPLE 1

Racemic 2-(N-n-propylamino)-5-methoxytetralin was resolved into its (-)and (+) isomers according to the method of Ten Hoeve and Wynberg (J.Org. Chem. 1985, 50, 4508), using the (+) isomer of4-(2-chlorophenyl)-5,5-dimethyl-2-hydroxy-1,3,2-dioxaphosphorinane2-oxide.

6.23 gm. (28.5 mmol) of racemic 2-(N-n-propylamino)-5-methoxytetralinand 7.7 gm. (27.8 mmol) of (+)4-(2-chlorophenyl)-5,5-dimethyl-2-hydroxy-1,3,2-dioxaphosphorinane2-oxide were dissolved by warming in 33 ml. of absolute alcohol and 10ml. of water. The heating was discontinued and the solution was allowedto cool while being stirred. After 15 min., the mixture was filtered offand washed with ether to yield 6.08 gm. of the salt (12.27 mmol, 43%).The salt was then stirred 30 min. with a solution of sodium hydroxidedissolved in 75 ml. water to which was added 25 ml. chloroform. Aftermixing, this was extracted with 2×50 ml. portions of chloroform. Theorganic extracts were washed with water, dried over magnesium sulfateand evaporated to dryness to yield 2.66 gm. (99%) of a slightly coloredoil. The optical rotation for 49 mg. in 5 ml. of methanol was -62.4°(578 nm). (The (+) isomer can be similarly isolated by using (-)4-(2-chlorophenyl)-5,5-dimethyl-2-hydroxy-1,3,2-dioxaphosphorinane2-oxide.)

The resultant isomers of 2-(N-n-propylamino)-5-methoxytetralin are thenconverted to (+) and (-)5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino)tetralin by themethods described in U.S. Pat. No. 5,564,628 herein incorporated byreference.

The pharmacological activities of the (+) and (-) stereoisomers weredetermined by examining their ability to displace the specific D-2dopamine receptor binding of a tritium-containing racemic mixture of5-hydroxy-2-(N-n-propyl-N-2-[2-thienyl]ethylamino)tetralin tohomogenates of calf brain corpus striatum. In this preparation, which isa modification of the one reported by Mulder et al. "Kinetic andPharmacological Profiles of the In-Vitro Binding of the Potent DopamineAgonist ³ H-N,N-dipropyl--5,6-dihydroxy-2-Aminotetralin to Rat StriatalMembranes," Eur. J. Pharmacol. 112 (1985) 73-79, for rat brain corpusstriatum, the tritium-containing racemic mixture had an affinityconstant (K_(d)) of 1.6 nanomoles and a βmax of 26.0 picomoles/gm, andhas a known high affinity for the post-synaptic receptors. The IC₅₀values (i.e., the concentration of drug required to inhibit the bindingof labelled drug by 50 percent) for the (-) and (+) isomers were 0.5 and71.0 nanomolar, respectively. Thus the (-) isomer is 140 times morepotent than the (+) isomer for binding to the postsynaptic receptors.

EXAMPLE 2

Turning behavior in 6-hydroxydopamine lesioned rats

Rotation after 6-hydroxy dopamine (6-OHDA) lesions have been induced wastested in male rats. 6-OHDA (dissolved in 1 μl of 0.9% NaC1) wasinjected into the substantia nigra at coordinates A-1.8, L-1.9, V-2.0(Kong and Klippel, The Rat Brain, a Stereotoxic Atlas of the Forebrainand Lower Parts of the Brain Stem (The Williams and Wilkins Company,Baltimore, 1963). To select a successfully denervated animal, rats weretested twice with intraparenteral injections of apomorphine at a dose of0.5 mg/kg of body weight at a 10 days interval. Rotational behavior wasrecorded in rotometers according to the method of Ungerstedt andArbuthnott (1970), "Quantitative Recording of Relational Behavior inRats after 6-hydroxydopamine Lesions of the Nigrostriatal DopamineSystem," Brain Res. 29, 485.

Comparison with apomorphine of (+) and (-) isomers of N-0437 at doses of1 and 10 μmol/kg is summarized in Table 2. The same contralateralturning as caused by apomorphine was caused by (-) N-0437, while (+)N-0437 up to a dose of 10 μmol/kg failed to produce significantcontralateral rotation. Thus, (-) N-0437 showed significant activity inthis postsynaptic dopamine receptor model while (+) N-0437 showed noeffect, thereby showing that the postsynaptic dopamine D₂ receptors maybe selectively activated.

                  TABLE 2                                                         ______________________________________                                                                       Net Number of                                           No. Animals  Dose     Contralateral                                  Comound  Tested       μmol/kg                                                                             Turns ± S.E.M.                              ______________________________________                                        Saline   4            0        0 ± 4                                       Apomorphine                                                                            10           1        240 ± 22                                    (+) N-0437                                                                             5            1        0 ± 5                                       (+) N-0437                                                                             6            10       3 ± 2                                       (-) N-0437                                                                             5            1        278 ± 39                                    (-) N-0437                                                                             5            10       201 ± 25                                    (±) N-0437                                                                          4            1        171 ± 32                                    ______________________________________                                    

Stereotyped Behavior in rats

Stereotyped behaviors such as continuous gnawing, biting, licking, areobserved following stimulation of postsynaptic dopamine receptors.(Ernst, A.M., 1967, Psychopharmacologia, 10:316). The method of van derWeide, J. et al (1986, Eur. J. Pharmacol., 125:273-282) was used toassess the intensity of stereotyped behavior in male rats injected i.p.with either (-) N-0437 or (+) N-0437. Male rats were injectedintraparenterally with either (+) or (-) N-0437 and placed separately incages. Stereotyped behavior was assessed and scored in semi-darknessevery 5 minutes using the scoring system of Costal, et al.,"Differential Activation by some 2-aminotetralin Derivatives of theReceptor Mechanisms in the Nucleus Accumbens of Rats Which MediateHyperactivity and Stereotyped Biting," European J. Pharmacol. (1977),41, 307. (-) N-0437 produced a half maximal effect at 1.7 μmol/kg.However, (+) N-0437 was inactive in this test for postsynaptic dopaminereceptor activity at doses up to 100 μg/kg.

EXAMPLE 3

The dopamine agonist apomorphine and the stereoisomers of N-0437 wereexamined for their ability to inhibit the calcium-dependent release of[³ H]ACh from rabbit striatal slices labelled with [³ H]choline, a knownin vitro test for post synaptic dopamine D₂ receptor agonists. Striatawere sliced with a tissue chopper incubated for 20 minutes at 37° C. inKrebs solution, composed of (in mM): Nac1, 108; Kc1, 4.7; glucose, 11.1;NaHCO₃, 25; Mgc1₂, 1.2; NaH₂, PO₄, 1.0; Cac1₂, 1.3; ascorbic acid, 0.11;and Na₂ EDTA, 0.004, that contained 0.1 μM 3H-choline. The tissues werewashed and individual slices were placed in glass superfusion chamberscontaining two platinum electrodes 30 mm apart. The tissues weresuperfused with Krebs solution at a rate of 1 ml/minute until thespontaneous outflow of radioactivity leveled off. ³ H-acetyl-cholinerelease was induced by field stimulation of 3HZ, 2 msec duration at acurrent of 20 mA. Samples were collected before, during, and afterstimulation. Two periods of stimulation were used; test drugs werepresent during the second stimulation. Released radioactivity wasdetermined by liquid scintillation counting.

The percent of total tissue radioactivity released by electricalstimulation above the spontaneous levels of release was 3.59±0.12% (n=3)and the ratio S₂ /S₁ was 0.95±0.03 (n=3). Apomorphine (0.1uM) and (-)N-0437 (0.01μM inhibited by about 50% the calcium-dependent release of[³ H]ACh elicited by electrical stimulation from rabbit striatal slices.The (+) isomer at a concentration of (0.1μM) almost completelyantagonized the inhibition of calcium-dependent release of [³ H]AChelicited by apomorphine (0.10μM) and (-) N0437 (0.0182 M).

EXAMPLE 4

Common marmosets were treated with sufficient MPTP to cause motordeficits: animals of either sex (weight range (289-390g) were treatedwith 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in single dosesof 1-2 mg/kg ip daily. Since the individual response of animals differedmarkedly, a variable dose regime was employed so as to render themparkinsonian. Following cessation of MPTP administration, animals wereallowed several week to recover from the acute effects of MPTPtreatment. There was a dosedependent reversal of motor deficitsfollowing both intraperitoneal injection of (-) N-0437 at dosages of0.1, 0.3, 0.5 and 0.7 mg/kg or oral administration at dosages of 0.1,0.3, 0.63 and 1.25 mg/kg of a racemic mixture of N-0437.

To test the effect of topical application, the (-) and (+) stereoisomersof N-0437 were separately administered to MPTP treated marmosets byapplying the isomers topically to the skin in alcoholic solutions.Twenty-four hours after application of the (-) isomer, the motordeficits induced by MPTP were clearly improved. Movements were faster,more coordinated, and less clumsy as determined by visual inspection.Measurement of locomotor activity in photocell cages showed the numberof light beam interruptions was almost restored to control levels up to32 hours after application of (-) N-0437. Animals treated with the (+)enantiomer showed neither a behavioral improvement nor a stimulation oflocomotor activity.

While particular embodiments of the invention have been described, itwill be understood, of course, that the invention is not limited theretosince many obvious modifications can be made and it is intended toinclude within this invention any such modifications as will fall withinthe scope of the appended claims. For example, this invention may beused to treat other diseases that are believed to involve dopaminergicresponse such as those treated by depressing prolactin levels, e.g.,hyperprolactinemia and breast cancer.

Having now described The invention, I claim:
 1. A method for treatingthe symptoms of parkinsonism in a mammal comprising administering tosaid mammal an effective amount of one or more compounds selected fromthe group consisting of the optically active or racemic compoundswherein the amount of the negative isomer is an amount effective totreat parkinsonism said compounds being represented by the formula:##STR13## wherein R₁ is ##STR14## X is sulfur, Y is hydroxy, and a is aninteger of from zero to 3,R₂, R₃ and R₄ are each selected from the groupconsisting of H and OA, A is H or is selected from the group consistingof hydrocarbyl radicals, ##STR15## R₅ is selected from the groupconsisting of hydrocarbyl radicals; n is an integer between 1 and 3; andR₆ is an alkyl chain having between 1 and 3 carbon atoms with theprovision that at least one of R₂, R₃ and R₄ is H, that at least one ofR₂, R₃ and R₄ is not H, and that R₂ and R₄ are not both OA, andpharmaceutically acceptable salts thereof.
 2. The method of claim 1wherein Y is zero and R₂ is oxygen.
 3. The method of claim 2 wherein Ais selected from the group consisting of phenyl and alkyl radicalshaving from 1 to 12 carbon atoms.
 4. The method of claim 3 wherein R₅ isselected from the group of alkyl or aryl radicals.
 5. The method ofclaim 4 wherein n is
 2. 6. The method of claim 5 wherein R₂, R₃ and R₄are selected from the group consisting of H and OA wherein A is H,##STR16##
 7. The method of claim 6 wherein said R₁ is selected from thegroup consisting of 2-thienyl and 3-thienyl.
 8. The method of claim 7wherein R₄ and R₃ are H and R₂ is OH.
 9. The method of claim 8 whereinR₁ is 2-thienyl and said mammal is a human.
 10. The method of claim 1wherein the compound is the optically active compound.
 11. The method ofclaim 9 wherein the compound is the optically active compound.
 12. Themethod of claim 11 wherein the optically active compound is the (-)isomer.
 13. The method of selectively activating the postsynaptic D₂dopamine receptors of a mammal, comprising administering to said mammalan effective amount of one or more compounds selected from the groupconsisting of optically active or racemic compounds wherein the amountof the negative isomer is an amount effective to treat parkinsonism ,said compounds being represented by the formula: ##STR17## wherein R₁ is##STR18## X is sulfur, Y is hydroxy, and a is an integer of from zero to3,R₂, R₃ and R₄ are each selected from the group consisting of H and OA,A is H or is selected from the group consisting of hydrocarbyl radicals,##STR19## R₅ is selected from the group consisting of hydrocarbylradicals; n is an integer between 1 and 3; and R₆ is an alkyl chainhaving between 1 and 3 carbon atoms with the provision that at least oneof R₂, R₃ and R₄ is H, that at least one of R₂, R₃ and R₄ is not H, andthat R₂ and R₄ are not both OA, and pharmaceutically acceptable saltsthereof.
 14. The method of claim 13 wherein Y is zero, and R₂ is oxygen.15. The method of claim 14 wherein A is selected from the groupconsisting of phenyl and alkyl radicals having from 1 to 12 carbonatoms.
 16. The method of claim 15 wherein R₅ is selected from the groupof alkyl or aryl radicals.
 17. The method of claim 16 wherein n is 2.18. The method of claim 17 wherein R₂, R₃ and R₄ are selected from thegroup consisting of OA and wherein A is H, ##STR20##
 19. The method ofclaim 18 wherein said R₁ is selected from the group consisting of2-thienyl and 3-thienyl.
 20. The method of claim 19 wherein R₄ and R₃are H and R₂ is OH.
 21. The method of claim 20 wherein R₁ is 2-thienyland said mammal is a human.
 22. The method of claim 13 wherein thecompound is the optically active compound.
 23. The method of claim 21wherein the compound is the optically active compound.
 24. The method ofclaim 23 wherein the optically active compound is the (-) isomer.
 25. Amethod for treating the symptoms of diseases involving dopaminergicresponse which comprises administering to a patient having the diseasean effective amount wherein the amount of the negative isomer is anamount effective to treat the disease of one or more compounds selectedfrom the group consisting of the isomers of optically-active or racemiccompounds represented by the general formula: ##STR21## wherein R₁ is##STR22## X is sulfur, Y is hydroxy, and a is an integer of from zero to3, R₂, R₃ and R₄ are each selected from the group consisting of H andOA, A is H or is selected from the group consisting of hydrocarbylradicals, ##STR23## R₅ is selected from the group consisting ofhydrocarbyl radicals; n is an integer between 1 and 3; and R₆ is analkyl chain having between 1 and 3 carbon atoms with the provision thatat least one of R₂, R₃ and R₄ is H, that at least one of R₂, R₃ and R₄is not H, and that R₂ and R₄ are not both OA, and pharmaceutically arenot both OA, and pharmaceutically acceptable salts thereof.
 26. Themethod of claim 25 wherein a is zero and R₂ is oxygen.
 27. The method ofclaim 26 wherein A is selected from the group consisting of phenyl andalkyl radicals having from 1 to 12 carbon atoms.
 28. The method of claim27 wherein A is selected from alkyl radicals having from 1 to 3 carbonatoms.
 29. The method of claim 28 wherein n is
 2. 30. The method ofclaim 18 wherein R₂, R₃ and R₄ are selected from the group consisting ofOA wherein A is hydrogen, and ##STR24## or ##STR25##
 31. The method ofclaim 25 wherein said R₁ is selected from the group consisting of2-thienyl and 3-thienyl.
 32. The method of claim 26 wherein R₄ and R₃are H and R₂ is OH.
 33. The method of claim 26 wherein R₁ is 2-thienyland said mammal is a human.
 34. The method of claim 25 wherein thecompound is the optically active compound.
 35. The method of claim 31wherein the compound is the optically active compound.
 36. The method ofclaim 35 wherein the optically active compound is the (-) isomer. 37.The method of claim 19 wherein said disease is hyperprolactinemia.